EU Commission President Jean-Claude Juncker shattered the fragile EU unity over the Salisbury attack today by congratulating Vladimir Putin on his election victory.

In a letter, Mr Juncker said: "I have always argued that positive relations between the European Union and the Russian Federation are crucial to the security of our continent."

The statement came despite Boris Johnson branding the election - which Putin won with more than 76% of the vote - a "coronation" amid claims of ballot box stuffing.

And the Organization for Security and Co-operation in Europe’s Office for Democratic Institutions and Human Rights, which sent observers to Russia, said there was a "lack of genuine competition" after Putin's main rival was barred from the race.

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Calling for “an Article V-B”, he wrote in the Telegraph: “A new doctrine would make clear that the use of a hybrid and undeclared attack would trigger a collective response from the alliance - a response that can be scaled up or down and, like the attack itself, stop short of all-out war.”

Meanwhile, Jeremy Corbyn plunged Labour into a fresh row after refusing to back Shadow Chancellor John McDonnell.

Mr McDonnell said of the attempted assassinations of Sergei Skripal and daughter Yulia that it was “highly likely this could have been a state execution”.

Jeremy Corbyn said he would 'do business' with Russia (Image: REUTERS)